Remote control system



Q 3 k w m m r i Wu. luvwm m fi u w Q r Feb. 22, 1966 I l l l L UnitedStates Patent Office Re. 25,959 Reissuecl Feb. 22, 1966 25,959 REMOTECONTROL SYSTEM Richard R. Ranson, Milwaukee, Wis, assignor t0 Cutler-Hammcr, Inc., Milwaukee, Wis., a corporation of Delaware Original No.3,204,169, dated Aug. 31, 1965, Ser. No. 179,313, Mar. 13, 1962.Application for reissue Sept. 29, 1965, Ser. No. 491,472

5 Claims. (Cl. 318264) Matter enclosed in heavy brackets appears in theoriginal patent hut forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

This invention relates to remote control electrical systems and moreparticularly to systems controllable from a remote station andcomprising load protecting means and means whereby an operator at theremote station is informed that such protective means has responded toan abnormal condition.

While not limited thereto, the invention is especially applicable tomotor control and protective systems for informing an operator at aremote station whenever motor operation is initiated whether an abnormalelectrical condition has occurred.

An object of the invention is to provide an improved remote controlsystem.

A more specific object of the invention is to provide a motor controlsystem having a remote control station with improved means for informingan operator whether an abnormal electrical condition has occurred.

Another specific object of the invention is to provide a motor controlsystem normally requiring a single switch- On operation to start themotor but requiring two succesive switch-on operations to start themotor after an overload protective device has tripped whereby anoperator at a remote station is advised when the first switch-onoperation does not start the motor that an abnormal condition hasoccurred.

Another specific object of the invention is to provide a motor controlsystem having a control station and overload protective devices withimproved means responsive to closure of a motor starting switch when anoverload protective device has not tripped for energizing the motor andbeing responsive to closure of such motor starting switch when anoverload protective device has tripped for resetting such overloadprotective device without energizing the motor thereby informing theoperator that an abnormal electrical condition has occurred,energization of the motor following such resetting requiring opening andreclosure of such motor starting switch.

A further specific object of the invention is to provide a simple andreliable motor control system whereby an operator at a remote stationcan control the motor and reset an overload protective device followingtripping thereof.

Other objects and advantages of the invention will hereinafter appear.

According to the invention, there is provided an alternating currentmotor of the three-phase type. The motor is illustrated as being adaptedfor alternately raising and lowering a movable gate of a dam. For thispurpose, the motor is provided with a control system having a raisecontactor and a main power contactor for connecting the motor to athree-phase electrical power supply source whereby to energize the motorfor rotation in one direction. A lower contacto-r and the main powercontactor connect the motor to the power supply source whereby toenergize the same for rotation in the opposite direction. The raise andlower contactors are controlled by respective raise and lower controlrelays. A control station mounted at a remote location is provided withraise and lower switches for controlling the aforementioned reverseenergizations of the motor and is also provided with a stop switch. Themotor is provided with an overload protective device having coilsconnected to at least two of its primary terminals. To afford resettingof the overload protective device from the remote control station thereis provide-d a reset coil and a control relay. The reset coil andcontrol relay are connected in the control system so that they arenormally ineffective but become effective after the overload protectivedevice trips. That is, depressing of a raise or lower switch normallycauses corre sponding motor operation. However, after the overloadprotective device trips, depressing of such switch causes resetting ofthe overload protective device. The switch must be pressed a second timeto energize the motor. The fact that the motor does not start when theswitch is pressed the first time indicates to the operator that theoverload protective device had tripper.

These and other objects and advantages of the invention and the mannerof obtaining them will best be understood by reference to the followingdetailed description of an embodiment of a remote control system takenin conjunction with the accompanying drawings, wherein:

The single figure diagrammatically illustrates a remote control systemconstructed in accordance with the invention.

Referring to the drawing, there is shown a control system for athree-phase alternating current induction motor EM which is adapted toraise and lower a gate. Motor EM is energized from a three-phasealternating current power supply source which is connectable to linesL1, L2 and L3. Line L1 is connected through normally open contacts M1and R1 of main contactor M and raise contactor R, respectively, and coil1 of a magnetic trip overload relay OL to a first terminal of motor EM.Line L2 is connected through normally open contact M2 of main contactorM to a second terminal of the motor. Line L3 is connected throughnormally open contacts M3 and R2 of main contactor M and raise contactorR, respectively, and through coil 2 of overload relay ()L to a thirdterminal of the motor.

A reversing circuit is provided by the connection of the junction ofcontacts M1 and R1 through a normally open contact L01 of a lowercontactor L0 to the junction of contact R2 and coil 2 and the connectionof the junctions of contacts M3 and R2 through a normally open contactL02 of lower contactor L0 to the junction of contact [M2] RI and [thesecond terminal of the motor] coil 1.

Lines L1 and L2 are also connected across the primary winding of atransformer TR, the opposite ends of a. secondary winding of suchtransformer being connected to conductors 3 and 4, respectively. Acontrol network CN is connected for energization across conductors 3 and4, such control network being upnder the control of a remote station RS.

Control network CN comprises the aforementioned main contactor M, raisecontactor R and lower' contactor LO. Control network CN is furtherprovided with a raise relay RR, a lower" relay LR, a control relay CRand an overload relay reset coil OLR for overload relay OL. Remotestation RS is provided with a stop switch S1, a raise switch S2 and alower switch S3, these switches being of the manual pushbutton type orthe like. The operating coil of raise relay RR is connected acrosssupply conductors 3 and 4 through stop switch S1 and raise switch S2 inseries. A maintaining circuit for the operating coil of raise relay RRextends through normally open contact R3 of raise contactor R in shuntof raise switch S2. The operating coil of lower relay LR is connectedacross supply conductors 3 and 4 through stop switch S1 and lower switchS3 in series. A maintaining circuit for the operating coil of relay LRextends through normally open contact L03 of lower contactor L in shuntof lower switch S3. The operating coil of main contactor M is connectedacross supply conductors 3 and 4 through normally closed contacts 0L1and CR1 of overload relay 0L and control relay CR, respectively, inseries connection and normally open contacts R and L05 of raisecont-actor R and lower contactor L0, respectively, the latter twocontacts R5 and L05 being in parallel connection in the circuit of theoperating coil of the main contactor. The operating coil of raisecontactor R is connected across supply conductors 3 and 4 throughnormally open contact RRl of raise" relay RR and normally closedcontacts 0L1 and CR1. The operating coil of lower" contactor L0 isconnected across supply conductors 3 and 4 through normally open contactLRl of lower relay LR and contacts 0L1 and CR1. The operating coil ofcontrol relay CR is connected to supply conductor 4 and through normallyclosed contacts R4 and L04 of raise" contactor R and lower contactor L0,respectively. where it divides. One branch extends through the operatingcoil of raise contactor R and normally open contact RRI of raise" relayRR to supply conductor 3. The other branch extends through the operatingcoil of lower contactor L0 and normally open contact LRl of lower" relayLR to supply conductor 3. Overload reset coil OLR is connected acrosssupply conductors 3 and 4 through normally open contact CR2 of controlrelay CR.

The operation of the system of FIGURE 1 will now be described.

Let it be assumed that a three-phase power supply source is connected topower supply lines L1, L2 and L3. As a result, supply conductors 3 and 4are energized through transformer TR. To operate motor EM in the forwarddirection, raise" switch S2 is pressed to close its contact and completean energizing circuit for the operating coil of raise relay RR throughstop switch 51. Contact RRl closes and completes an energizing circuitfor the operating coil of raise contactor R through contacts 0L1 andCR1. Contacts R1 and R2 in the motor circuit close. Contact R3 closes tocomplete a maintaining circuit for the [operatipg] operating coil ofraise relay RR in shunt of raise" switch S2 whereupon the latter may bereleased. Contact R4 opens to [interrupts] interrupt the energizingcircuit of the operating coil of control relay CR. Contact R5 closes tocomplete an energizing circuit for the operating coil of main contactorM through contacts 0L1 and CR1. Contacts M1, M2 and M3 close to connectmotor EM to the power supply source and to initiate operation thereof toraise the gate.

To stop the motor, stop switch S1 is pressed to interrupt themaintaining circuit for the operating coil of raise relay RR extendingthrough contact R3. Contact RRl opens to interrupt energization of raisecontactor R. Contacts R1 and R2 open to disconnect motor EM from thepower supply source. Contact R5 opens to interrupt energization of theoperation coil of main contactor M. Contacts M1, M2 and M3 open tofurther disconnect motor EM from the power supply source. The motorstops.

Let it be assumed that motor EM is running in the forward direction ashereinbefore described and that due to an overload condition either orboth of coils l and 2 of overload relay 0L are energized to open contact0L1. This interrupts encrgization of contactors M and R. Contacts R1.R2. M1, M2 and M3 open to disconnect the motor from the power supplysource. Contact R3 opens to interrupt the maintaining circuit for relayRR. Contacts R5 and RRl open and contact R4 closes.

To reset overload relay 0L, raise switch S2 is pressed to close itscontacts and to complete an energizing circuit for the operating coil ofrelay RR. Contact RRl closes to complete an energizing circuit for theoperating coil of control relay CR through the operating coil of contactor R and contacts L04 and R4 across supply conductors 3 and 4.Contact CR1 opens to prevent short circuiting and consequentdccnergization of the operating coil of relay CR. Contact CR2 closes tocomplete an energizing circuit for overload reset coil OLR across supplyconductors 3 and 4. Overload reset coil OLR recloses contact 0L1. Underthis condition, the operating coils of relays RR and CR and reset coilOLR remain energized as long as switch S2 is maintained closed. Due tothe voltage drop in the operating coil of relay CR, the operating coilof raise" contactor R does not energize in series therewith and themaintaining circuit for the operating coil of relay .RR through contactR3 is not completed. When switch S2 is released to open its contact, theoperating coil of relay RR is deenergized. Contact RRl opens todeenergize the operating coil of relay CR and contact CR2 opens todeenergize reset coil OLR. Contact 0L1 remains closed. This returns thecircuit to its normal condition shown in the drawing wherein it is readyfor another operation of the motor.

To operate the motor in the reverse direction, lower switch S3 ispressed to close its contact and complete an energizing circuit throughstop switch S1 for the operating coil of lower relay LR. Contact LRlcloses to complete an energizing circuit for lower contactor L0 throughcontacts 0L1 and CR1. Contacts L01 and L02 close to complete points inthe reverse energizing circuit of the motor. Contact L03 closes tocomplete a maintaining circuit for the operating coil of relay LR inshunt of switch S3. Contact L04 opens to prevent energization of theoperating coil of relay CR and contact L05 closes to complete anenergizing circuit for the operating coil of main contact M throughcontacts 0L1 and CR1. Contacts M1, M2 and M3 close to connect the motorto the power supply source for operation in the reverse direction. Tostop the motor, stop switch S1 is momentarily pressed to interruptenergization of relay RR, contactor L0 and contactor M thereby todisconnect the motor from the power supply source.

If an overload condition occurs, overload relay 0L operates ashereinbefore described to open contact 0L1. As a result, contactors L0and M are decnergized to disconnect the motor from the power supplysource. Contact L03 opens to deenergize the operating coil of relay LR.

To reset the overload relay. switch S3 is momentarily pressed to closeits contact and to energize the operating coil of relay LR. Contact LRIcloses to complete an energizing circuit for the operating coil of relayCR through the operating coil of contactor L0 and contacts L04 and R4.Relay CR has a smaller coil than contactor R or L0 and functions ashcreinbefore described to energize reset coil OLR thereby to closecontact 0L1. The operating coil of contactor L0 is larger than and doesnot energize in series with the operating coil of relay CR. Thus, whenswitch S3 is released, the operating coils of relays LR and CR and resetcoil OLR are [denergized] zleelzergr'zed to return the system to thenormal condition shown in the drawing wherein it is ready for furtheroperation of the motor by pressing either switch S2 or S3. It will beapparent that the overload relay can be reset to close contact 0L1 bymomentarily pressing either switch S2 or S3. It will also be apparentthat resetting of the overload relay does not cause rcopcration of themotor. Instead, either switch S2 or S3 must be pressed to reset. theoverload relay following which the appropriate switch S2 or S3 must bepressed to operate the motor in the desired direction.

From the foregoing description, it will be apparent that all of thenecessary control functions of the motor can be performed from theremote station RS. The motor can be operated in either the forward orreverse direction by pressing switch S2 or S3 to raise or lower the gateon the dam. The motor can be stopped by pressing switch S1. If theoverload relay trips, the operator at the remote station will beinformed of this when restarting of the motor is attempted. Thus,failure of the motor to start when either switch S2 or S3 is pressedinforms the operator that an overload condition has occurred. Theoperator at the remote station can reset the overload relay by pressingeither switch S2 or S3. Release of such switch and a second depressingthereof or pressing of the other switch causes motor operation.

While the system hereinbefore described is effectively adapted tofulfill the objects stated, it is to be understood that I do not intendto confine my invention to the particular preferred embodiment of remotecontrol system disclosed, inasmuch as it is susceptible of variousmodifications without departing from the scope of the appended claims.

I claim:

1. A remote control system comprising:

(a) a power supply source;

(b) an electroresponsive load;

(c) and means for connecting said load to said source to causeenergization thereof comprising:

(d) a control circuit;

(e) a remote station connected for controlling said control circuit;

(f) protective means responsive to an abnormal electrical condition insaid system for operating said control circuit to cause disconnection ofsaid load from said source, said protective means having a trippedcondition which it assumes in response to such abnormal condition and analternative reset condition wherein said control circuit is operable tocontrol energization of the load;

(g) said remote station comprising switch means effective upon firstswitch-on operation thereof when said protective means is in its resetcondition to cause operation of said connecting means and thereby toenergize said load;

(h) and means in said control circuit effective when said protectivemeans is in its tripped condition for causing operation of saidprotective means to its reset condition in response to a similar firstswitch-on operation of said switch means without energizing said loadthereby to indicate to the operator that an abnormal condition hasoccurred.

2. In a motor control system in combination:

(a) a power supply source;

(b) a motor;

(c) means for connecting said motor to said source to cause operationthereof comprising a control circuit and a remote station connected forcontrolling said control circuit;

((1) and protective means responsive to a motor overload condition foroperating said control circuit to cause disconnection of the motor fromsaid source, said protective means having a tripped position which itassumes in response to such overload condition and in which it remainsand a reset position wherein said control circuit is operable to controlenergization of the motor;

(e) said remote station comprising a switch normally operable when saidprotective means is in its reset position to operate said controlcircuit to cause energization of the motor;

(f) and said control circuit comprising means responsive to firstclosure of said remote switch when said protective means is in itstripped position for resetting said protective means without energizingsaid motor thereby to indicate to the remote operator that an overloadcondition has occurred, means responsive to another closure of saidremote switch following resetting of said protective means for operatingsaid connecting means to energize the motor.

3. A system for controlling a motor from a remote 5 location comprising:

(a) a control station at a remote location comprising a switch;

(b) a control circuit connected to said switch and comprising meansresponsive to closure of said switch for connecting the motor to anelectrical power supply source;

(0) means tripping in response to a motor overload condition foroperating said means thereby to discon meet the motor from the powersupply source;

(d) electroresponsive reset means for said overload means;

(e) control means for said reset means, said control means beingnormally ineffective when said overload means is reset;

(f) means responsive to closure of said switch while said overload meansis tripped for operating said control means to cause resetting of saidoverload means;

(g) and means responsive to operation of said control means forpreventing operation of said connecting means;

4. The invention defined in claim 3, wherein said preventing meansresponds to reopening of said switch to recondition said connectingmeans for operation on the next closure of said switch.

5. A system for controlling a reversible motor from a remote locationcomprising:

(a) a control station at a remote location having a pair of switchesselectively operable for controlling reverse rotations of the motor;

(b) first means responsive to closure of a first one of said switchesfor causing energization of the motor for rotation in one direction;

(c) second means responsive to closure of the other switch alternativelyfor causing energization of the motor for rotation in the otherdirection;

(d) overload protective means in the motor energizing circuit trippingin response to an overload condition for deenergizing the energized oneof said first and second means thereby to deenergize the motor and forpreventing reenegization of either said first or second means until saidoverload means is reset;

(e) normally inetfective resetting control means rendered effective inthe tripped condition of said overload means and being responsive tofirst closure of either one of said switches for causing resetting ofsaid first or second means until after the closed switch is repoened;

(f) and said first and second means being responsive to selective secondclosure of a switch for causing energization of the motor for rotationin the selected direction.

References Cited by the Examiner The following references, cited by theExaminer, are

of record in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,310,139 2/ 1943 Wickerham 3l874 X 2,405,0537/1946 Posselt M 318-264 X 3,075,134 1/1963 Manney 318476 ORIS L. RADER,Primary Examiner.

I. BERENZWEIG, R. COOKE, Assistant Examiners.

